Some insect pests can be reduced in the fall as well. Insects such as twig girdlers over-winter in tree branch debris and many plant pathogens can survive the winter in fallen leaves, residual stalks and rotten fruit in the garden. Raking up and removing this debris will reduce the insects emerging next spring.
If you have a backyard compost pile, the garden debris you remove is a great addition. A well maintained pile will heat up and completely decompose the debris in a few years. The heat-up process will destroy most disease-causing organisms.